This invention relates to a method of treating fabrics in the rinse cycle of a textile laundering operation with an antimicrobial agent in order to eliminate odor caused by microbial growth.
An antimicrobial is an agent that destroys or inhibits the growth of microorganisms. The major classes of microorganisms are bacteria, fungi including mold and mildew, yeasts, and algae. Microorganisms can be found in the air, the waters, the human body, soil, wastes, and on all surfaces. The organisms are deposited from the air, food and drink spills, dust, dirt and tracked in soil, and from human excreta such as sweat, urine, and feces. Organisms grow and multiply when there is available a nutrient source of food such as dirt, organic or inorganic material, and living tissue. For growth and multiplication, organisms also require warm temperatures, and moisture. When these conditions exist, microorganisms thrive and flourish. Microbial growth, however, leads to many problems such as unpleasant odors ranging from stale to musty and mildew-like, to putrid and foul smelling, resembling ammonia. The growths also produce unsightly stains, discoloration, and deterioration of many surfaces and materials in which they come into contact. A more serious disadvantage of microbial growth is the production of pathogenic microorganisms, germs, their metabolic products and their somatic and reproductive cell parts, which contribute to the spread of disease, infection, and disorders.
Antimicrobial agents are chemical compositions that are used to prevent such microbiological contaminations by inhibiting, killing and/or removing them and neutralizing their effects of deterioration, defacement, odor, disease or other negative effects. Particular areas of application of antimicrobial agents and compositions are, for example, cosmetics, disinfectants, sanitizers, wood preservation, food, animal feed, cooling water, metalworking fluids, hospital and medical uses, plastics and resins, petroleum, pulp and paper, textiles, latex, adhesives, leather and hides, and paint slurries. In the area of medical applications, antimicrobials are often used as powders, in lotions, creams, ointments and/or delivered in a variety of solvents or directly as over-the-counter or ethical drugs to alleviate, mediate, cure and/or protect people or other animals from disease or cosmetic conditions. Of the diverse categories of antimicrobial agents and compositions, quaternary ammonium compounds represent one of the largest of the classes of antimicrobial agents in use. At low concentrations, quaternary ammonium type antimicrobial agents are bacteriostatic, fungistatic, algistatic, sporostatic, and tuberculostatic. At medium concentrations they are bactericidal, fungicidal, algicidal, and viricidal against lipophilic viruses. Silicone quaternary ammonium salt compounds are well known as exemplified by U.S. Pat. No. 3,560,385, issued Feb. 2, 1971, and the use of such compounds as antimicrobial agents is taught, for example; in a wide variety of patents such as U.S. Pat. Nos. 3,730,701, issued May 1, 1973, and 3,817,739, issued Jun. 18, 1974, where the compounds are used to inhibit algae; 3,794,736, issued Feb. 26, 1974, and 3,860,709, issued Jan. 14, 1975, where they are employed for sterilizing or disinfecting a variety of surfaces and instruments; and 3,865,728, issued Feb. 11, 1975, where the compounds are used to treat aquarium filters. Published unexamined European Application No. 228464 of Jul. 15, 1987, teaches that microorganisms on multi-cellular plants can be killed by the application thereto of an aqueous mixture of a surfactant and an organosilicon quaternary ammonium compound. U.S. Pat. No. 4,564,456, issued Jan. 14, 1986, discloses organosilanes as anti-scale agents in water systems. In a particular application of an antimicrobial silicone quaternary ammonium compound, a paper substrate is rendered resistant to the growth of microorganisms in U.S. Pat. No. 4,282,366, issued Aug. 4, 1981. In U.S. Pat. No. 4,504,541, issued Mar. 12, 1985, an antimicrobial fabric is disclosed which is resistant to discoloration and yellowing by treatment of the fabric with a quaternary ammonium base containing an organosilicone. U.S. Pat. No. 4,615,937, issued Oct. 7, 1986, as well as its companion U.S. Pat. No. 4,692,374, issued Sep. 8, 1987, relate to wet wiper towelettes having an antimicrobial agent substantive to the fibers of the web and being an organosilicon quaternary ammonium compound. In a series of Burlington Industries, Inc. U.S. Pat. Nos. 4,408,996, issued Oct. 11, 1983, 4,414,268, issued Nov. 8, 1983, 4,425,372, issued Jan. 10, 1984, and 4,395,454 , issued Jul. 26, 1983, such compounds are disclosed to be useful in surgical drapes, dressings, and bandages. This same assignee also discloses these compounds as being employed in surgeons' gowns in U.S. Pat. Nos. 4,411,928, issued Oct. 25, 1983, and 4,467,013, issued Aug. 21, 1984. Organosilicon quaternary ammonium compounds have been employed in carpets, in U.S. Pat. No. 4,371,577, issued Feb. 1, 1983; applied to walls, added to paints, and sprayed into shoes, in U.S. Pat. No. 4,394,378, issued Jul. 19, 1983; formulated as aqueous emulsions in U.S. Pat. No. 4,631,273issued Dec. 23, 1986; applied to polyethylene surfaces and used in pillow ticking in U.S. Pat. No. 4,721,511, issued Jan. 26, 1988; in flexible polyurethane foams of fine-celled, soft, resilient articles of manufacture in U.S. Pat. No. 4,631,297, issued Dec. 23, 1986; and mixed with a surfactant in British Patent No. 1,386,876, of Mar. 12, 1975, and in Japanese Kokai Application No. 58-156809, filed Aug. 26, 1983, of Sanyo Chemical Industries, Ltd. Some general, more domestic type applications of these compounds, has included their use in a dentifrice as in U.S. Pat. No. 4,161,518 issued Jul. 17, 1979; in a novel laundry detergent in U.S. Pat. No. 4,557,854, issued Dec. 10, 1985; as a hair conditioner in U.S. Pat. No. 4,567,039 , issued Jan. 28, 1986; and in a soft contact lens disinfectant solution in U.S. Pat. No. 4,615,882, issued Oct. 7, 1986. In U.S. Pat. No. 4,614,675, issued Sep. 30, 1986, properties can be influenced by mixing the silicone quaternary ammonium salt compounds with certain siloxanes.
Other typical uses of organosilicon quaternary ammonium compounds in accordance with the prior art can be seen from U.S. Pat. Nos. 4,005,024; '025; '028; and '030; each issued on Jan. 25, 1977, and relating to hard surface rinse aids and detergents for hard surfaces. Contact lenses are treated with an organosilane in U.S. Pat. No. 4,472,327, issued Sep. 18, 1984. In U.S. Pat. No. 4,682,992, issued Jul. 28, 1987, glass spheres are treated with the compounds and employed as filters. The compounds are used to treat swine dysentery in U.S. Pat. No. 4,772,593, issued Sep. 20, 1988; in a wet wiper in U.S. Pat. No. 4,781,974, issued Nov. 1, 1988; applied to a polyester fabric in U.S. Pat. No. 4,822,667, filed Apr. 18, 1989; and adhered to polyamide yarn in U.S. Pat. No. 4,835,019, issued May 30, 1989. In Canadian Patent No. 1,217,004, granted Jan. 27, 1987, organosilane quaternary ammonium compounds are formulated into bleaches that are applied to hard surfaces such as bath tubs, wash basins, toilets, drains, and ceramic tile floors.
Modern washing machines work automatically and the operator places the laundry in the machine, pours in the detergent, and sets the controls. One set of controls determines whether the machine employs hot, warm, or cold water. Water enters the machine through hoses connected to the hot and cold water pipes. The operator also sets controls in order to select the length of washing and rinsing time, and the amount of water that enters the machine. The machine is powered by an electric motor and includes a filter that removes lint, and automatic dispensers for bleach and fabric softeners. A wash cycle typically includes four stages. In the wash cycle, after water fills the wash tub, an agitator reverses direction alternately and moves the laundry through the water and detergent, and forces water through the items of laundry. The washer is then emptied of all of the wash liquor in the spin cycle and the clothes are spun to remove excess water. In the rinse cycle, clean water is added along with the fabric softener and the clothes are again agitated. The washer is emptied of rinse liquor and the clothes are spun in a final spin cycle during which time excess water is removed and pumped out of the machine through a drain hose. The clothing is then ready to be removed from the machine and dried in a dryer or hung on a clothesline until dry.
Fabric treatments for use in such machines are well known in the art. For example, in British Patent No. 1,549,180, issued Jul. 25, 1979, Dumbrell et al disclose a fabric softener which includes, in addition to the softening benefit, the additional benefits of easier ironing, antistatic properties, pleasanter feel, and soil release properties. The additional benefits are stated to be derived from the inclusion along with a cationic quaternary ammonium fabric softening agent, of a silicone compound which is said to be an aqueous emulsion of a linear siloxane.
Specifically, Dumbrell et al relate to fabric softening compositions that include an aqueous dispersion of a cationic softening compound, and a silicone emulsion. The cationic compound is disclosed to be one or more or mixtures of a combination of quaternary mono-ammonium compounds such as tallowtrimethylammonium chloride, and ditetradecyldimethylammonium chloride; quaternary imidazolinium compounds; polyammonium compounds such as acid salts of diamine compounds, and polyamine salts; and polyalkyleneimine salts. The silicone emulsion is preferably a linear dialkyl or alkylaryl siloxane which may be partially or wholly fluorinated, or substituted with cationic nitrogen groups. The viscosity is disclosed to be, at twenty-five degrees Centigrade, at least one hundred and up to eight thousand centistokes. The weight ratio of siloxane content of the emulsion to the dispersion is five to one, to one to one-hundred. Representative compositions are said to be cationic emulsion polymerized dimethylsiloxanes, with the emulsifying agent being, for example, ditallowyldimethylammonium chloride; quaternized polysiloxanes such as dipyridinium polydimethylsiloxane; and aminofunctional linear polysiloxanes such as polydimethylsiloxanes containing dimethylaminopropyl groups.
It is not new to employ an organosilicon quaternary ammonium compound in a laundering environment. For example, in U.S. Pat. No. 4,557,854, issued Dec. 10, 1985, a powdered heavy duty laundry detergent is disclosed which contains insoluble particulate materials, the surfaces of which have been treated with a silane. It is also not new to employ organosilicon compounds in the rinse cycle of a fabric treating laundering operation. Aminofunctional polysiloxanes have been included as an additive in the rinse cycle in the aforementioned British Patent No. 1,549,180, granted Jul. 25, 1979 to Dumbrell et al. What is believed to be new and unique and what is disclosed in the present invention, however, is the concept of employing an organosilane which is an organosilicon quaternary ammonium compound in the rinse cycle of a fabric laundering operation.
There is a basic distinction between the aminofunctional polysiloxane employed in the rinse cycle in the British Patent 1,549,180, and the organosilane quaternary ammonium compound of the present invention when it is employed in the rinse cycle. While both compositions are organosilicon compounds, and while both are employed in the rinse cycle, the two compositions function in the rinse cycle in an entirely different fashion one from the other. For example, in the rinse cycle, the silane end of the organosilicon quaternary ammonium molecule of the present invention is substantive to natural textile surfaces such as cotton, wool, and jute, but the siloxane end of the aminofunctional organosilicon molecule of Dumbrell is not substantive to such surfaces. The organofunctional end of the organosilane quaternary ammonium molecule of the present invention is substantive to wetted surfaces and anionic surfaces such as synthetic textiles of the types nylon and polyester, but the aminofunctional end of the polysiloxane molecule of Dumbrell et al is not substantive to such surfaces. Further, the organosilane quaternary ammonium compounds of the present invention are antimicrobially active and hence are capable of killing microorganisms and preventing their proliferation, while the aminofunctional polysiloxanes of Dumbrell et al are not active antimicrobials. In addition, because of the substantive textile affinity of both ends of the molecule of the organosilane quaternary ammonium compounds of the present invention, the antimicrobial treatments rendered by these compounds are durable. This the aminofunctional polysiloxane of Dumbrell et al is incapable of duplicating.
The "unbound" antimicrobials of the prior art are not the equivalent of the "bound" antimicrobial organosilane of the present invention because the unbound antimicrobials do not perform substantially the same function, in substantially the same way, to produce substantially the same results, as do the bound silanes of the present invention. The function differs because the bound antimicrobial is permanent whereas the unbound types are easily washed away or rubbed from the surface. The compounds of the present invention are not only durable but retain their antimicrobial activity after some ten laundering cycles, and only slightly diminish in their activity after as many as twenty-five laundering cycles. The bound silanes of the present invention retain an effective kill level of microorganisms. The manner in which the bound silane functions differs from the unbound types, since the bound silane attaches itself to the surface to which it is applied, whereas the unbound types are mere coatings which are not substantive. This is significant since the silane antimicrobial will continue to prevent reinfestation, and enables one to utilize the intrinsic antimicrobial activity of the silane treated surface to kill transient microbes, long after the unbound types of antimicrobials have been depleted of their activity. Further, the bound silanes of the present invention destroy, reduce, and inhibit the growth and multiplication of bacteria, fungi, and other pathogenic microorganisms, by the disruption of cell membranes, a mechanism absent from conventional unbound antimicrobial materials. The results produced by the bound silanes is not the same as the results produced by the unbound types, since the bound silanes provide a prolonged antimicrobial activity and continue to kill and inhibit the proliferation of potentially destructive microorganisms, versus mere temporary and superficial protection offered by the unbound category of material.
Thus, it should be apparent that the method of the present invention in employing the bound antimicrobially active organosilicon quaternary ammonium compounds is far removed from methods that have been previously disclosed by the prior art.
Among the numerous attempts to alleviate the problems of microorganisms on surfaces have involved the use of soaps, detergents, and surface cleaners. The treatments, however, have for the most part included an unbound category of antimicrobial which is not actually bonded to the surface sought to be treated, and therefore is consumed by the microorganisms, with the result that the unbound antimicrobial is depleted and washed away during routine cleansing. As this diffusion continues, the concentration of the active ingredient becomes diluted below effective levels, with the result that the microorganisms sought to be inhibited, adapt and build up a tolerance, becoming immune to what was once an effective treatment dose. Such unbound diffusible antimicrobials have therefore been found to be limited in their ability to offer broad spectrum control of microorganisms, in contrast to the bound type of antimicrobial which remains chemically attached to the surface to which it is applied providing for a surface that prevents recolonization by the microflora associated therewith. Diffusing types of antimicrobials also often suffer from the propensity to transfer percutaneously, giving rise to sensitization and irritation immunological responses, and raising serious questions as to their ultimate fate within the body and body systems.
Bound antimicrobials kill organisms on contact and continue to kill organisms without being diffused or leached from the surface. Thus, the bound antimicrobial leaves behind an effective level of active ingredient and is able to control a broad spectrum of microorganisms including gram negative and gram positive bacteria, mold, mildew, fungi, yeast, and algae. An exemplary category of bound antimicrobial is an alkoxysilane quaternary ammonium compound, and such alkoxysilane quaternary ammonium compounds have been found to be more effective at reducing the number of microorganisms, and inhibiting microbially generated odors, than conventional organotin compounds and other organic quaternary ammonium compounds. The silanes of the present invention immobilize on surfaces and bond thereto to provide a coating of immobilized antimicrobial, unlike conventional materials.
In the present invention, this bound characteristic of alkoxysilane quaternary ammonium compounds, as well as their capabilities of performing at effective kill levels beyond prior art types of compositions, is taken advantage of in the treatment of fabrics, in order to reduce or substantially eliminate the incidence of microorganisms, germs, their metabolic products and their somatic and reproductive cell parts, which contribute to the spread of such microbes.